The Ultraviolet Calibration of the Hubble Space Telescope. II. A Correction for the Change in Sensitivity of the SWP Camera on the IUE

Abstract

The IUE data on standard stars that will be the basis of UV absolute photometric calibration for the Hubble Space Telescope must be corrected for the changes that are apparent in the low-dispersion spectra of the five standard stars. A set of 895 spectra is presently analyzed in order to determine the change in sensitivity of the SWP camera for the first 8 years of flight operations. Sensitivity loss is noted to be most acute at the shortest (1400-1500 A) wavelengths, as well as beyond 1800 A, where total degradation often exceeds 10 percent.